Blocking air returns / static pressure

[Norm01]

I have a brand new Bryant 289B with Evolution thermostat. We are just in a heat wave and my second floor of my house is staying a few degrees warmer than my first. Common problem I know. My static pressure is low at .22, I have one return on the main floor and 4 on the second floor. Would blocking the return on the main floor and forcing cold return onto the second floor be wise. Does blocking too much return increase static pressure.

[Six]

Blocking returns DECREASES static.

I wouldnt advise it

[second opinion]

Blocking returns DECREASES static.

I wouldnt advise it

Are you sure?

[Norm01]

Thanks, I blocked it temporarily and noticed the static went down by about .02. What is the ratio needed from return main trunk to return grill size, is it 1:1. My return is 12x24 or 288 sq.in. If I block one return and the remaining open ones equal 288 or more is this safe or do I need more.

[udarrell]

I have a brand new Bryant 289B with Evolution thermostat. We are just in a heat wave and my second floor of my house is staying a few degrees warmer than my first. Common problem I know. My static pressure is low at .22, I have one return on the main floor and 4 on the second floor.

Would blocking the return on the main floor and forcing cold return onto the second floor be wise. Does blocking too much return increase static pressure.

IMHO; That static pressure was NOT taken correctly; there is no way you will get .22" of static on an A/C coil system.

Depending on the tonnage of the E-Coil, the evaporator coil pressure-drop alone could be considerably more than .22" of an inch.

The Return Air negative-side is added to the positive Supply-Side for the External Static Pressure (ESP) result.

The supply & return need to be in balance to equal the total CFM required for the area to be cooled.

Even if you enlarged the 2nd floor's return area to equal the total CFM of that systems tonnage requirements, - there wouldn't be enough Supply ducting to coincide with the super enlarged Return ducting; also needed with a Zoned System.

You could run some more Supplies to the 2nd floor area & then add Returns to equal or exceed the SA. That would increase the amount of CFM 'To & From' the 2nd floor.

You could install a two zoned air flow system with a room thermostat also on the 2nd floor. When the 2nd floor was calling it would shift a much larger percentage of air flow to that floor & much less to the 1st floor area.

I'd just try adjustable dampers near the 1st floor take-offs; lowest cost remedy.

[beenthere]

Thanks, I blocked it temporarily and noticed the static went down by about .02. What is the ratio needed from return main trunk to return grill size, is it 1:1. My return is 12x24 or 288 sq.in. If I block one return and the remaining open ones equal 288 or more is this safe or do I need more.

You got a false reading on the static pressure then.

[Norm01]

Thanks for the input guys. The static pressure is given by the Evolution thermostat so it may or may not coincide with the way the pro's measure it. I have a 3Ton system with a matched 4Ton coil, ducts are large and originally designed for 120,000Btu furnace. I closed two supplies on the first floor and SP went to .35.

I guess my brain was still frozen from the winter as I solved my problem. I keep my fan in auto for the winter. Because of my open concept house and the fact that heat rises I forgot I needed to keep the fan on in summer cooling mode. This is mixing the air and I now have less than 1 degree F between floors. I was at more than 5.

[tipsrfine]

Thanks for the input guys. The static pressure is given by the Evolution thermostat so it may or may not coincide with the way the pro's measure it. I have a 3Ton system with a matched 4Ton coil, ducts are large and originally designed for 120,000Btu furnace. I closed two supplies on the first floor and SP went to .35.

I guess my brain was still frozen from the winter as I solved my problem. I keep my fan in auto for the winter. Because of my open concept house and the fact that heat rises I forgot I needed to keep the fan on in summer cooling mode. This is mixing the air and I now have less than 1 degree F between floors. I was at more than 5.

Keep an eye on your electrical usage; air infiltration/exfiltration can increase quite a bit when the fan is running and can increase electrical usuage.